The study found that those who were spanked were more likely to have abused drugs or attempted suicide.

And that was with other factors -- including more severe physical or emotional abuse -- taken into account.

The findings don't prove that spanking, per se, led to adulthood mental health issues, said Andrew Grogan-Kaylor, one of the researchers.

But the study is far from the first to suggest spanking can have long-term consequences.

For years, numerous studies have linked spanking to negative effects on children's mental health, as well as adults', said Grogan-Kaylor, an associate professor of social work at the University of Michigan.

There may still be a cultural debate over the merits of spanking, he noted. But as far as research goes, there's plenty of evidence tying spanking to negative effects.

The findings, published in the journal Child Abuse & Neglect, are based on survey responses from over 8,300 California adults.

Overall, 55 percent said that as children, they were spanked at least a few times a year.

And those people were 37 percent more likely to say they'd ever attempted suicide, versus adults who'd never been spanked as kids. They were also one-third more likely to have abused drugs, and 23 percent more likely to drink in "moderate to heavy" amounts.

Of course, Grogan-Kaylor said, it's difficult to weed out the effects of spanking from the rest of a person's childhood environment.

But the link between spanking and mental health issues held up even after the researchers weighed some other factors -- such as people's education level and race.

Adults who'd suffered physical and emotional abuse as kids also had more mental health problems. But that did not explain the risk connected to spanking, the study found.

"There does seem to be a unique effect of spanking," Grogan-Kaylor said.

The American Academy of Pediatrics (AAP) has long advised against spanking, citing a range of reasons. Among them: Repeated spanking can teach children that aggression is the solution to conflicts, and may worsen any behavioral issues.

Instead, the group encourages parents to use non-physical types of discipline, such as "time-outs" or taking a privilege away for a short time.

Dr. Benjamin Siegel is a member of the AAP's Committee on Psychosocial Aspects of Child and Family Health.

"Many adults think, 'I was spanked as a kid and I'm OK,' " said Siegel, who wasn't involved in the study.

Plus, he noted, parents may find that when they want to stop an undesired behavior, spanking works pretty quickly.

"But from a medical and social development point of view, spanking is not good," Siegel said.

That said, simply telling parents "don't spank" may not suffice: Many parents may need help with putting other types of discipline into practice, according to Siegel.

It can be easier said than done for parents with their own mental health issues, and those living in poverty, for example.

"I can't tell you how much poverty can impact a person's parenting abilities," Siegel said.

He said pediatricians should, and do, ask parents about their own stress levels and mental health -- and refer them for help, if needed. Local communities often have resources, including programs that teach parenting skills.

"It's not just a matter of prohibiting spanking," Siegel said. "It's also about improving overall parenting skills."

Grogan-Kaylor agreed. "Positive parenting really does pay off in the long run," he said.